Apple has released iOS 8 today and it brings with it many new features that you can read about here. But, before you update your device, there are a couple of steps you need to take to make sure you don't lose any data.
First thing you need to do is backup your phone. In theory, you should be ok not doing this but if you are like us, when we installed the GM of iOS 8 using iTunes, it crashed and we had to wipe our phone.
There are two backup options: using iCloud, or plugging your phone in to iTunes. For a faster and comprehensive backup, we suggest using your computer and iTunes to do a full backup of your device. We also recommend that your device has at least 50% charge before updating too.
Once you have done all the necessary steps, you can tap on 'Settings' on your iPhone, tap on 'General' then tap 'Software Update'. After doing this, your iOS device will begin to search for the update.
Another other option is to open up iTunes, plug your phone in and then click on your device at the top and then click 'Check for Updates'.
Your last option is to use the download links from an Apple developer account if you participate in that program.